In the production of a usable synthesis gas by the combustion of a carbonaceous fuel, the process is operated most effectively in a gasifier or reactor under high temperature and high pressure conditions. For example, for the production of a gas from a particulated coal or coke, a preferred operating temperature range of about 2400.degree. to 2600.degree. F. is maintained, at a pressure of between about 5 to 250 atmospheres.
The harsh operating conditions prevalent in such a method, and in particular the wide temperature variations experienced, imposes a severe strain on many segments of the gasifier or reactor unit.
The present invention is addressed to an improvement in the structure of a gasifier, and particularly in the gasifier's quench ring and water distribution manifold. The latter by its inherent function, is exposed to maximum temperature conditions and destructive gases. This occurs by virtue of the hot synthesis gas which comes in direct contact with the quench ring and manifold as the hot effluent passes from the combustion chamber, into a cooling zone or quenching zone.
U.S. Pat. No. 4,444,726 illustrates a quench ring arrangement embodying a separable, two segment design. A sealing gasket compressed between the respective segments, maintains the latter in a relatively seal tight relationship. The sealing gasket, however, is exposed to hot effluent gas and is subject to wide temperature variations. These are factors which will limit the gasket's usable life as an effective sealant member.
In the usual reactor structure, the combustion chamber within the reactor shell is lined with a refractory material to avoid thermal damage to the shell. This refractory material can take the form of individual bricks or can be in the configuration of a unitary member shaped of a castable refractory material. In either instance, the refractory blocks or members are combined and shaped to define the gasifier's constricted throat.
The refractory throat members are normally supported in such a manner that they can be removed if required for repair or replacement. One form of support resides in placing the quench ring in a position that it will support the throat. Thus, the quench ring, which is positioned by the shell wall, will locate the supported throat. During a shut down period, however, it is more than likely that in the course of a normal cooling period, metallic segments of the gasifier such as the quench ring and its ancillary parts will cool rapidly. This allows quick access to the reactor interior parts for performing necessary repair or maintenance work.
Where the reactor's quench ring requires removal for repair or replacement, it is necessary to first detach the refractory blocks which make up the constricted throat. These non-metallic members take a much longer period of time to cool down than does the metallic quench ring. It can therefore be several days before one can obtain safe access to the reactor interior to permit removal of the quench ring. Furthermore, removal of the throat refractory necessitates the expense of its replacement because used fire brick once disturbed, cannot be reassembled correctly (due to distortions and slag accumulations that develop while in service).
Toward overcoming this problem of unnecessary gasifier down time and throat refractory replacement, the present invention embodies a gasifier structure wherein the constricted throat between the combustion chamber and the quench chamber, is formed of one or more refractory blocks. The latter are supported in place by a segmented quench ring having a separable manifold section. Thus, when the exposed manifold section of the quench ring becomes damaged due to thermal stresses or the like, the damaged part can be readily removed without disturbing the quench ring which remains in place supporting the throat.
The water carrying manifold section which maintains a coolant stream against the reactor's dip tube, is detachably fixed to the water conducting quench ring. In a preferred construction, the respective manifold and quench ring, are provided with a thermally resistant gasket compressed between mating surfaces to minimize the flow of heat therebetween. Thus, the refractory member or members which define the constricted throat need not be disturbed when the manifold is removed. Further, the thermally resistant gasket between the mating or engaged members minimizes heat transfer therebetween.
In terms of economics, a reactor's shut down period for repair purposes, can be reduced by several days as a result of use of the disclosed separable quench ring structure. It has been determined for comparison purposes, that a typical gasification reactor can be accessed for internal repair to the quench ring, within two days when the instant quench ring is a part of the unit. If the refractory neck has to be removed to allow access to the quench ring, the total time required for refractory cooling and refractory replacement upon a new quench ring could be five days or more.
It is an object of the invention therefore, to provide a novel quench ring assembly for a gasification reactor, which facilitates removal and repair of the reactor's internal elements.
A further object is to provide a segmented quench ring which is fabricated to permit ready access to a reactor's damaged internal parts.
Another object is to provide a multi-segmented quench ring for a gasification reactor, which can be disassembled and removed piecemeal from the refractory's interior.